Concrete seawall with precast components

ABSTRACT

Seawalls and methods for making seawalls are disclosed. A seawall may include a concrete footing, with a first plurality of anchorages disposed in the concrete footing. A plurality of precast concrete tee beams may include single-tee beams and/or double-tee beams. Flanges of the tee beams may be positioned to form seaward and landward faces of the wall, and stems of the tee beams may be coupled to the footing between the seaward and landward faces. A second plurality of anchorages may be disposed at tops of the stems. Elongate steel components extend through the stems, and are tensioned between the first plurality of anchorages and the second plurality of anchorages. Interior fill may be disposed between the seaward and landward faces. One or more wave deflectors may be disposed above the tee beams.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/988,308 entitled “CONCRETE SEAWALL WITH PRECASTCOMPONENTS” and filed on Mar. 11, 2020 for me: John W. Babcock, which isincorporated herein by reference.

FIELD

This invention relates to concrete seawalls and more particularlyrelates to concrete seawalls with precast components.

BACKGROUND

Seawalls may provide from erosion and/or flooding of a coastline.Similar structures may be used at saltwater or freshwater shorelines,riverbanks, or the like, as dikes or levees. Cast-in-place concreteseawalls may provide long-lasting coastline protection, but may betime-consuming or expensive to build.

SUMMARY

A seawall, in various embodiments, includes a concrete footing. In someembodiments, a seawall includes a plurality of precast concrete teebeams, including single-tee beams and/or double-tee beams. In someembodiments, flanges of the tee beams are positioned to form seaward andlandward faces of the wall, and stems of the tee beams are coupled tothe footing between the seaward and landward faces. In some embodiments,a seawall includes interior fill disposed between the seaward andlandward faces.

A method for making a seawall, in various embodiments, includesexcavating a location for placing a concrete footing for a wall. In someembodiments, a method includes installing a sheet pile wall extendingdownward from the location. In some embodiments, a method includesinstalling a concrete footing at the location. The concrete footing mayinclude a first plurality of anchorages for threadbars. In someembodiments, a method includes coupling threadbars to the anchorages. Insome embodiments, a method includes placing a plurality of precastconcrete tee beams over the threadbars. The tee beams may includesingle-tee beams and/or double-tee beams. The tee beams may bepositioned so that the threadbars extend through stems of the tee beams,and the flanges of the tee beams are positioned to form seaward andlandward faces of the wall. In some embodiments, a method includescoupling a second plurality of anchorages to the threadbars above thestems of the tee beams. In some embodiments, a method includestensioning the threadbars between the first plurality of anchorages andthe second plurality of anchorages. In some embodiments, a methodincludes installing interior fill between the seaward and landwardfaces.

A seawall, in some embodiments, includes a concrete footing. In someembodiments, a first plurality of anchorages is disposed in the concretefooting. In some embodiments, a seawall includes a plurality of precastconcrete tee beams, including single-tee beams and/or double-tee beams.In some embodiments, flanges of the tee beams are positioned to formseaward and landward faces of the wall, and stems of the tee beams arecoupled to the footing between the seaward and landward faces. In someembodiments, a second plurality of anchorages is disposed at tops of thestems. In some embodiments, elongate steel components extend through thestems, and are tensioned between the first plurality of anchorages andthe second plurality of anchorages. In some embodiments, interior fillis disposed between the seaward and landward faces. In some embodiments,one or more wave deflectors are disposed above the tee beams.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readilyunderstood, a more particular description of the invention brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating one embodiment of a seawallunder construction;

FIG. 2 is a cross section view illustrating the seawall of FIG. 1 at onestage of construction;

FIG. 3 is a cross section view illustrating the seawall of FIG. 1 at asubsequent stage of construction;

FIG. 4 is a cross section view illustrating the seawall of FIG. 1 at asubsequent stage of construction;

FIG. 5 is a perspective view illustrating another embodiment of aseawall under construction;

FIG. 6 is a cross section view illustrating the seawall of FIG. 5 at onestage of construction;

FIG. 7 is a cross section view illustrating the seawall of FIG. 5 at asubsequent stage of construction;

FIG. 8 is a cross section view illustrating the seawall of FIG. 5 at asubsequent stage of construction; and

FIG. 9 is a cross section view illustrating another embodiment of aseawall.

DETAILED DESCRIPTION

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment, but mean “one or more but not all embodiments” unlessexpressly specified otherwise. The terms “including,” “comprising,”“having,” and variations thereof mean “including but not limited to”unless expressly specified otherwise. An enumerated listing of itemsdoes not imply that any or all of the items are mutually exclusiveand/or mutually inclusive, unless expressly specified otherwise. Theterms “a,” “an,” and “the” also refer to “one or more” unless expresslyspecified otherwise.

Furthermore, the described features, structures, or characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. In the following description, numerous specific details areincluded to provide a thorough understanding of embodiments of theinvention. One skilled in the relevant art will recognize, however, thatthe invention may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of theinvention.

The schematic flow chart diagrams included herein are generally setforth as logical flow chart diagrams. As such, the depicted order andlabeled steps are indicative of one embodiment of the presented method.Other steps and methods may be conceived that are equivalent infunction, logic, or effect to one or more steps, or portions thereof, ofthe illustrated method. Additionally, the format and symbols employedare provided to explain the logical steps of the method and areunderstood not to limit the scope of the method. Although various arrowtypes and line types may be employed in the flow chart diagrams, theyare understood not to limit the scope of the corresponding method.Indeed, some arrows or other connectors may be used to indicate only thelogical flow of the method. For instance, an arrow may indicate awaiting or monitoring period of unspecified duration between enumeratedsteps of the depicted method. Additionally, the order in which aparticular method occurs may or may not strictly adhere to the order ofthe corresponding steps shown.

As used herein, a list with a conjunction of “and/or” includes anysingle item in the list or a combination of items in the list. Forexample, a list of A, B and/or C includes only A, only B, only C, acombination of A and B, a combination of B and C, a combination of A andC or a combination of A, B and C. As used herein, a list using theterminology “one or more of” includes any single item in the list or acombination of items in the list. For example, one or more of A, B and Cincludes only A, only B, only C, a combination of A and B, a combinationof B and C, a combination of A and C or a combination of A, B and C. Asused herein, a list using the terminology “one of” includes one and onlyone of any single item in the list. For example, “one of A, B and C”includes only A, only B or only C and excludes combinations of A, B andC. As used herein, “a member selected from the group consisting of A, B,and C,” includes one and only one of A, B, or C, and excludescombinations of A, B, and C.” As used herein, “a member selected fromthe group consisting of A, B, and C and combinations thereof” includesonly A, only B, only C, a combination of A and B, a combination of B andC, a combination of A and C or a combination of A, B and C.

A seawall, in various embodiments, includes a concrete footing. In someembodiments, a seawall includes a plurality of precast concrete teebeams, including single-tee beams and/or double-tee beams. In someembodiments, flanges of the tee beams are positioned to form seaward andlandward faces of the wall, and stems of the tee beams are coupled tothe footing between the seaward and landward faces. In some embodiments,a seawall includes interior fill disposed between the seaward andlandward faces.

In some embodiments, the flanges of the tee beams are positioned so thatthe seaward and landward faces of the wall are slanted and the wall isthicker at a base of the wall than at a top of the wall. In someembodiments, the stems of the tee beams extend further away from theflanges of the tee beams at the base of the wall than at the top of thewall.

In some embodiments, a first plurality of anchorages is disposed in theconcrete footing, and a second plurality of anchorages is disposed attops of the stems. In some embodiments, elongate steel components extendthrough the stems, and are tensioned between the first plurality ofanchorages and the second plurality of anchorages. In some embodiments,the elongate steel components include threadbar. In some embodiments,the elongate steel components comprise multi-wire steel strand.

In some embodiments, one or more wave deflectors are disposed above thetee beams. Wave deflectors may include concrete that is shaped todeflect water. In some embodiments, the tee beams forming the landwardface of the wall are shorter than the tee beams forming the seaward faceof the wall. In some embodiments, an upper portion of the wall isdisposed above the tee beams forming the landward face of the wall, andbehind the tee beams forming the seaward face of the wall. In someembodiments, the upper portion of the wall includes cast-in-placeconcrete. In some embodiments, the tee beams forming the landward faceof the wall are equal in height to the tee beams forming the seawardface of the wall.

In some embodiments, the interior fill includes cast-in-place concreteand/or vibration-compacted crushed rock. In some embodiments, a sheetpile wall extends downward from the footing to prevent erosion of soilunder the footing. In some embodiments, the footing includescast-in-place concrete. In some embodiments, the footing includesconcrete tee beams. In some embodiments, a plurality of drains extendthrough the wall, and are sloped to drain water from a landward side tothe seaward side. In some embodiments, the plurality of drains mayinclude at least one upper drain that includes an inlet disposed above asoil level at the landward face of the wall. In some embodiments, theplurality of drains may include at least one lower drain that includes afiltered inlet disposed below the soil level.

A method for making a seawall, in various embodiments, includesexcavating a location for placing a concrete footing for a wall. In someembodiments, a method includes installing a sheet pile wall extendingdownward from the location. In some embodiments, a method includesinstalling a concrete footing at the location. The concrete footing mayinclude a first plurality of anchorages for threadbars. In someembodiments, a method includes coupling threadbars to the anchorages. Insome embodiments, a method includes placing a plurality of precastconcrete tee beams over the threadbars. The tee beams may includesingle-tee beams and/or double-tee beams. The tee beams may bepositioned so that the threadbars extend through stems of the tee beams,and the flanges of the tee beams are positioned to form seaward andlandward faces of the wall. In some embodiments, a method includescoupling a second plurality of anchorages to the threadbars above thestems of the tee beams. In some embodiments, a method includestensioning the threadbars between the first plurality of anchorages andthe second plurality of anchorages. In some embodiments, a methodincludes installing interior fill between the seaward and landwardfaces.

In some embodiments, a method further includes comprising disposing aplurality of drains extending through the interior fill between theseaward and landward faces. In some embodiments, a method furtherincludes coupling one or more wave deflectors to the wall above the teebeams.

A seawall, in some embodiments, includes a concrete footing. In someembodiments, a first plurality of anchorages is disposed in the concretefooting. In some embodiments, a seawall includes a plurality of precastconcrete tee beams, including single-tee beams and/or double-tee beams.In some embodiments, flanges of the tee beams are positioned to formseaward and landward faces of the wall, and stems of the tee beams arecoupled to the footing between the seaward and landward faces. In someembodiments, a second plurality of anchorages is disposed at tops of thestems. In some embodiments, elongate steel components extend through thestems, and are tensioned between the first plurality of anchorages andthe second plurality of anchorages. In some embodiments, interior fillis disposed between the seaward and landward faces. In some embodiments,one or more wave deflectors are disposed above the tee beams.

FIG. 1 depicts one embodiment of a seawall 100 under construction. Theseawall 100 is depicted in a perspective view, with a seaward side tothe upper right, and a landward side to the lower left. The seawall 100is depicted under construction, with different portions of the wall 100at different stages of construction, so that certain internal componentsof the seawall 100 are visible. Terms such as “seawall,” “seaward,” and“landward” are used herein to refer, generally, to structures thatprovide erosion protection and/or flooding protection where water meetsland. Thus, in one embodiment, a “seawall” as disclosed herein may be alevee along a riverbank, and may nevertheless be referred to herein as a“seawall” with a “seaward” side and a “landward” side, despite thefreshwater context. Similarly, a wall providing erosion protection in aprotected area like a harbor may be referred to as a “seawall” despitethe lack of direct exposure to the sea. In the depicted embodiment, theseawall 100 includes wave deflectors 102, a cast-in-place upper portion104, landward tee beams 106, a footing 108, seaward tee beams 110,interior fill 112, threadbar 114, and a sheet pile cut-off wall 116,which are described below.

The sheet pile cut-off wall 116 is disposed at the base of the seawall100, and extends downward from the footing 108 to prevent erosion ofsoil under the footing 108. A sheet pile wall 116, in variousembodiments, may include interlocking (or otherwise connected) sheetpiles, which may be driven into the ground by a vibratory hammer,hydraulic press, or the like, or may be placed in an excavation such asa narrow trench and grouted for stability. Various types of sheet pilewalls 116 or methods of constructing a sheet pile wall 116 may be usedwith various embodiments of a seawall 100, to prevent water seepage andsoil erosion under the wall 100.

In some embodiments, a sheet pile wall 116 may be omitted, and theproblems associated with water seepage and soil erosion under the wall100 may be solved in another way. For example, a ditch may be excavateddownward from the location where the footing 108 will be installed, andmay be filled with concrete that is then coupled to the footing 108, sothat the concrete-filled ditch prevents water seepage and soil erosionunder the wall. In various embodiments of a wall 100, various other orfurther structures for preventing water seepage and/or soil erosionunder the wall 100 may be used in place of a sheet pile wall 116.

In some embodiments, a location may be excavated for placing a concretefooting 108 for a wall 100. For example, at a shoreline where a seawallis to be installed, a shallow cut or trench may be excavated to providea level location where the footing 108 of the wall 100 may be disposed.(Crushed rock may also be installed into such an excavation as a basefor the footing 108 in some embodiments, and the landward side of theexcavation may be backfilled after construction of the wall 100.) When alocation is excavated for placing a concrete footing 108, a sheet pilewall 116 may be installed extending downward from that location, and thefooting 108 may then be installed at that location.

The footing 108, in various embodiments, provides a foundation for othercomponents of the wall 100. In the depicted embodiment, the footing 108is cast-in-place concrete. In another embodiment, the footing 108 may beformed from precast concrete sections. In some embodiments, the footing108 is coupled to the sheet pile cut-off wall 116. For example, sheetpile cut-off wall 116 may be installed so that upper portions of sheetpiles extend up from the soil. A cast-in-place concrete footing 108 maycast so that concrete is contact with or surrounding the exposedportions of the sheet piles. Alternatively, precast concrete sectionsfor a footing 108 may include a void shaped to engage or surround theexposed portions of the sheet piles.

In various embodiments, the exterior of the wall 100 is formed ofconcrete tee beams 106, 110. Although the term “tee beam” is sometimesused to refer specifically to a single-tee beam with a T-shaped crosssection, terms such as “tee beam” or “tee” are used herein to refer tomore generally to a single-tee beam, a double-tee beam with a TT-shapedcross section, a triple-tee beam and/or another multi-tee beam. For asingle-tee beam with a T-shaped cross-section, a stem or web correspondsto the stem of the T, and a flange corresponds to the crossbar of the T.Similarly, for a double-tee beam with a TT-shaped cross-section, aflange corresponds to a crossbar across the top of both Ts, and twostems or webs correspond to the stems of the two Ts. In the depictedembodiment, the tee beams 106, 110 are double-tee beams. In anotherembodiment, the tee beams 106, 110 may be single-tee beams, a mixture ofsingle-tee and double-tee beams, or the like.

In various embodiments, tee beams 106, 110 may be precast concrete. Invarious embodiments, precast concrete components may be cast usingreusable molds, forms, or beds, then moved (as solid components) to thelocations where they will be installed, coupled together, and/or coupledto other components. By contrast, some concrete components that are notprecast may be cast in place by building casting forms on site andpouring concrete into the forms to cure and remain in place. However,building forms for casting concrete in place may be time-consuming,expensive, or difficult to do in a location that is exposed to wavesfrom the sea. Thus, in some embodiments, the use of precast concrete teebeams 106, 110 may allow a wall 100 to be built more quickly and atlower cost than a cast-in-place wall.

In the depicted embodiment, the flanges of tee beams 106, 110 arepositioned to form the seaward and landward faces of the wall 100, andthe stems of the tee beams 106, 110 are coupled to the footing 108between the faces (e.g., in the interior of the wall 100). In thedepicted embodiment, the flanges of tee beams 106, 110 are positioned sothat the seaward and landward faces of the wall 100 are slanted, and thewall 100 is thicker at the base than at the top. Accordingly, in furtherembodiments, the stems of the tee beams 106, 110 may extend further awayfrom the flanges at the base of the wall 100 than at the top. Thus, thestems are slanted relative to the flanges (or, equivalently, the flangesare slanted relative to the stems). The result is that when the teebeams 106, 110 are installed with the stems vertical, at the interior ofthe wall 100, the flanges form slanted seaward and landward faces of thewall 100. A casting bed for casting standard concrete single-tee ordouble-tee beams may be modified to have slanted portions for castingsingle-tee or double-tee beams with slanted stems.

Various types of precast concrete beams may be post-tensioned by castinga sleeve or duct into the concrete along the length of the beam,inserting post-tensioning steel (such as multi-wire steel strand orsteel threadbar) through the sleeve or duct, and tensioning thepost-tensioning steel between anchorages at either end of the beam. Thesleeve or ducts may be pressure-grouted so that the tensioned steel isbonded to the surrounding grout. Alternatively, grouting may be omitted,so that the tensioned steel (e.g., threadbar or multi-wire strand)within a sleeve or duct is not bonded to surrounding grout or concretealong its length between anchorages. At the anchorages, tension in thesteel is transmitted to (and balanced by) compression in the concrete.The resulting compression of the concrete strengthens it against tensileforces that will occur when the beam is used.

In various embodiments, post-tensioning steel for a wall 100 may includea plurality of elongate steel components that extend through stems ofthe tee beams 106, 110. Elongate steel components for post-tensioningmay be threadbar, multi-wire steel strand or the like. In someembodiments, components for post-tensioning may be made of materialsother than steel. For example, fiberglass, carbon fiber, or othersynthetic material may be used to form elongate components forpost-tensioning. Sleeves or ducts to receive the elongate steelcomponents may be cast into the precast concrete tee beams 106, 110, andthe steel may be subsequently inserted into the sleeve or duct.Alternatively, the elongate steel components for post-tensioning may becast into the precast concrete tee beams 106, 110, but separated fromthe concrete by a sleeve, duct, spiral wrap, or the like, so that thepost-tensioning steel does not bond to the concrete, allowing thepost-tensioning steel to be subsequently tensioned between twoanchorages.

In the depicted embodiment, tee beams 106, 110 include sleeves or ductsfor post-tensioning steel along the length of the stems. By disposingone set of anchorages for the post-tensioning steel in the footing 108and another set of anchorages for the post-tensioning steel at the topof the stems, the post-tensioning steel may be used for the dual purposeof compressing and strengthening the tee beams 106, 110 and coupling thetee beams 106, 110 to the footing 108. Various further subject matterrelating to walls and/or to coupling and post-tensioning concretecomponents, is included in U.S. patent application Ser. No. 17/187,402entitled “STRAND-TO-THREADBAR COUPLER BLOCK FOR PRESTRESSED CONCRETE”and filed on Feb. 26, 2021 for John W. Babcock, which is incorporatedherein by reference.

In the depicted embodiment, the post-tensioning steel is threadbar 114.Threadbar 114, in various embodiments, may include a steel bar that isfully threaded, threaded at ends but smooth along the length to preventbonding to concrete, or the like. Threads allow threadbar 114 to betensioned by applying torque to threadbar nuts at anchorages. Varioustypes of threadbar 114, or other forms of post-tensioning steel such asmulti-wire strand, will be recognized as suitable for prestressing orcompressing concrete in a seawall 100. To construct the wall 100, thesheet pile cut-off wall 116 and the footing 108 are placed, threadbars114 are coupled to anchorages in the footing 108, and tee beams 106, 110are placed on or over the threadbars 114. Tee beams 106, 110 may includeducts or sleeves for threadbars 114, and may be placed by lifting thetee beams 106, 110 above the threadbars 114, then lowering the tee beams106, 110 so that the ducts or sleeves surround the threadbars 114.Assembly of components may take place in another order. For example,threadbars 114 may be inserted into ducts or sleeves in tee beams 106,110, then moved into place and torqued to anchorages in the footing 108.

In the depicted embodiment, interior fill 112 is disposed between theseaward and landward faces of the wall 100, (e.g., between inward facingsurfaces of the tee beams 106, 110). In one embodiment, interior fill112 may be cast-in-place concrete. In another embodiment, interior fill112 may be ballast. In another embodiment, interior fill 112 may becrushed rock (e.g., gravel) compacted by vibration to form a solid wallinterior. For example, interior fill 112 may be three-quarter inch minusfill, compacted by vibration. Interior fill 112 may be installed betweenthe seaward and landward faces of the wall 100, after the tee beams 106,110 are coupled to the footing 108, and may then be cast, compacted orthe like.

In some embodiments, a seawall 100 may be built so that the seaward sideis exposed and visible from the water (at least at low tide). Thelandward side may be at least partially below ground. For example, thefooting 108 may be installed in an excavated shallow cut or trench, andthe volume between the landward side of the seawall 100 and the shore(at ground height) may be backfilled with soil, gravel, or the like.Backfill may cover the landward side of the seawall 100 to a desiredheight.

In the depicted embodiment, the tee beams 106 that form the landwardface of the wall 100 are shorter than the tee beams 110 that form theseaward face of the wall 100. Tee beams 106, 110 (e.g., single-teeand/or double-tee beams) may be precast for multiple walls in the samecasting bed, and may have thus have a standardized or uniform exteriorfinish or texture rather than a particular exterior finish or texturedesired for one of the walls. Thus, in the depicted embodiment, thedouble-tee beams 106 at the landward side are short so as to be at orbelow the eventual elevation of backfill material, without being visiblefrom the landward side, and an upper portion 104 of the wall 100 iscast-in-place concrete.

The upper portion 104 of the wall 100, in the depicted embodiment, isdisposed above the tee beams 106 forming the landward face of the wall100 and behind (to the landward side of) the tee beams 110 forming theseaward face of the wall 100. An upper portion 104 of the wall 100,above the interior fill 112 and the landward tee beams 106, may becast-in-place concrete. For example, a form for casting concrete may beaffixed to the beams 106 at the landward side, and the upper portion 104may be cast in place between the forms and the taller seaward tee beams110. Casting an upper portion 104 of a wall 100 in place may allow adesired exterior finish or texture to be formed on the visible upperportion 104 of the wall 100.

One or more wave deflectors 102 may be disposed at the top of the wall100, above the tee beams 106, 110. In various embodiments, wavedeflector(s) 102 may be concrete components that are shaped, curved, orangled to deflect water, to prevent waves from overtopping the wall 100.In some embodiments, wave deflectors 102 may be precast concretecomponents. In another embodiment, wave deflectors 102 may be cast inplace with the upper portion 104 of the wall 100. In some embodiments,precast concrete wave deflectors 102 may be coupled to post-tensioningsteel (e.g., threadbar 114) that secures one or more of the tee beams110 to the footing 108. For example, multi-wire strand or threadbar 114may extend through a tee beam 110 from an anchorage in the footing 108to an anchorage at the top of the tee beam 110, and may bepost-tensioned prior to placing the interior fill 112. The anchorage atthe top of the tee beam 110 may be include or be coupled to a mountingpoint where a steel component (e.g., threadbar) within the wavedeflector 102 may be mounted to the top of the wall 100. For example, inthe depicted embodiment where a tee beam 110 is post-tensioned usingthreadbar 114, a threadbar-to-threadbar coupler may be disposed at thetop of the threadbar 114 as a mounting point for coupling threadbar in awave deflector 102 to the wall 100. In another embodiment, where a teebeam 110 is post-tensioned using multi-wire steel strand, astrand-to-threadbar coupler as disclosed in the incorporated patentapplication may optionally be disposed at the top of the strand as amounting point for coupling threadbar in a wave deflector 102 to thewall 100.

FIGS. 2-4 depict the seawall 100 of FIG. 1 in cross section, at threesuccessive stages of construction. The seaward side is to the right, andthe landward side is to the left. Referring to FIG. 2, the sheet-pilecut-off wall 116 is provided, and a crushed stone layer 210 is providedas a base for the footing 108. The footing 108 is cast in place,including a plurality of lower anchorages 208 and ducts 206 forthreadbar 114 (or multi-wire strand). Threadbars 114 are insertedthrough the ducts 206 and coupled to the lower anchorages 208. Seawardtee beams 110 include ducts 202 for sleeved or bare threadbar 114 (ormulti-wire strand), similar to the ducts 206 in the footing 108. Theseaward tee beams 110 are lowered onto the threadbars 114 so that thethreadbars 114 are in the ducts 202. Upper anchorages for the threadbars114 are disposed at tops of the stems of the tee beams 110, and arecoupled to the threadbars 114. The threadbars 114 are post-tensioned atthe upper anchorage, to compress and strengthen the seaward tee beams110. For example, nuts at the upper anchorages may be torqued to tensionthe threadbars 114 between the upper and lower anchorages. In someembodiments, the seaward tee beams 110 may be formed with access voids204 to allow post-tensioning of shorter threadbars 114 that do notextend all the way to the top of the wall 100.

Referring to FIG. 3, the landward tee beams 106 include ducts 202similar to the ducts 202 in the seaward tee beams 110. The landward teebeams 106 are coupled to the footing 108 and compressed viapost-tensioning of threadbar 114 as described above for the seaward teebeams 110. Drains 302 (e.g., PVC pipe) may be included allowing water(e.g., from waves that overtop the wall 100) to drain from the landwardside back to the seaward side. With the tee beams 106, 110 and thedrains 302 placed, the interior fill 112 may then be added. In thedepicted embodiment, the interior fill 112 is cast-in-place concrete,poured and cast into the space between the landward tee beams 106 andthe seaward tee beams 110. In another embodiment, interior fill 112 maybe vibration-compacted gravel, or other fill material, disposed in thespace between the landward tee beams 106 and the seaward tee beams 110.

Referring to FIG. 4, once the interior fill 112 (not shown in FIG. 4) isplaced to approximately the top elevation of the landward tee beams 106,upper drains 404 (e.g., PVC pipe similar to the drain 302) may beplaced, and the upper portion 104 of the wall 100 may be cast in place(e.g., using forms on the landward side). Wave deflectors 102 may thenbe coupled to the upper portion 104 of the wall 100, the threadbars 114,and/or the seaward tee beams 110. At the lower drains 302, “burritodrain” inlets 406 may be provided including perforated tubing wrapped incloth or another textile to let water in but keep dirt out, surroundedby a water-permeable crushed rock bed. Fill material 402 may then beadded to backfill the landward side of the wall 100.

In the depicted embodiment, the drains 302, 404 extend through the wall100, and are sloped to drain water from the landward side of the wall100 to the seaward side. The drains may be placed before the interiorfill 112 and/or the cast-in-place upper portion 104 of the wall 100 sothat they slope through the interior fill 112 and/or the cast-in-placeupper portion 104. One or more upper drains 404 may include inlets thatare disposed above a soil level at the landward face of the wall 100.For example, in the depicted embodiment, upper drain 404 has an inletabove the level of fill material 402. One or more lower drains 302 mayinclude filtered inlets 406 disposed below soil level (e.g., below thelevel of fill material 402). Filtered inlets 406 may be textile-coveredperforated tube “burrito-drain” inlets as described above, or mayinclude another type of filter to exclude the soil or fill material 302from the lower drains 302. In various embodiment, providing drains 302,404 above and below the soil level may mitigate erosion, by allowingwater from waves that overtop the wall 100 to rapidly drain out throughthe upper drains 404, while allowing remaining water that seeps into thesoil to drain out through the lower drains 302.

In some embodiments, drains 302, 404 may be omitted. Various other orfurther ways of allowing water to drain may be provided in variousembodiments. For example, if interior fill 112 is free-draining fillthat allows water to pass through it, filter fabric may be installed atvertical joints between adjacent tee beams 106, 110, allowing water todrain through the wall by passing through the vertical joints and theinterior fill 112.

FIGS. 5-8 depict another embodiment of a seawall 500. FIG. 5 depicts theseawall 500 in a perspective view, with FIGS. 6-8 depicting crosssections of the seawall 500 at different stages of construction. As inFIGS. 1-4, the seaward side is depicted to the right (or, in theperspective view, to the upper right), and the landward side is depictedto the left (or, in the perspective view, to the lower left). Theseawall 500, in the depicted embodiment, may be substantially similar tothe seawall 100 described above with reference to FIGS. 1-4, includingwave deflectors 502, a cast-in-place upper portion 504, landward teebeams 506, a footing 508, seaward tee beams 510, interior fill 512,threadbar 514, a sheet pile cut-off-wall 516, a crushed stone layer 610,threadbar anchorages 608, ducts 602, 606, access voids 604, drains 702,804, “burrito drain” inlets 806 and fill material 802, which may besubstantially as described above apart from certain differences whichare described below.

Referring to FIG. 5, the footing 508 in the depicted embodimentcomprises precast concrete tee beams, which may be single-tee beams,double-tee beams, or the like as described above with reference to teebeams 106, 110. The tee beams for the footing 508 may be cast with avoid in the flange to admit the top end of the sheet pile cut-off wall516. In some embodiments, a footing 508 made of precast concrete teebeams may be constructed more quickly than the cast-in-place footing 108described above with reference to FIG. 1.

In the depicted embodiment, the landward tee beams 506 are a mixture ofsingle-tee beams 506 a and double-tee beams 506 b. In variousembodiments, the landward tee beams 506 and/or the seaward tee beams 510may include single-tee beams, double-tee beams, or a mixture of single-and double-tee beams. In some embodiments, single-tee beams may be usedwhere a larger double-tee beam would be difficult to place, or tofacilitate alignment deviations where the wall 500 changes direction.

The tee beams 506 forming the landward face of the wall 100, in thedepicted embodiment, are equal in height to the tee beams 510 formingthe seaward face of the wall 100. Equal height tee beams 506, 510, invarious embodiments, may be formed in the same or substantially similarbeds or molds to be the same nominal height (apart from differences thatarise in casting, or may be substantially the same height allowing forsome variation or tolerance (e.g., a 1% variation in height, a 2%variation in height, a 5% variation in height) such that beams withinthe tolerance can still be described as equal in height. With thelandward tee beams 506 in the depicted embodiment extending to the sameheight as the seaward tee beams 510, the landward tee beams 506 arevisible above the fill material 802. In some embodiments, usingequal-height landward and seaward tee beams 506, 510 may allowcast-in-place portions of the wall 500 such as the upper portion 504 tobe cast between the landward and seaward tee beams 506, 510 instead ofby using a form at the landward side. However, exterior finish optionsmay be more limited when using landward tee beams 506 that are visibleabove the fill material 802.

The interior fill 512, in the depicted embodiment, isvibration-compacted crushed rock, or a self-compacting rock fill. Forexample, interior fill 512 may be three-quarter inch minus crushed rock.Fill material that is more flowable than crushed rock or self-compactingrock, such as concrete interior fill 112 or lightweight cellularconcrete, may be used with a cast-in-place footing 108, but excessconcrete may run out between the stems of precast double-tees in footing508. If concrete or lightweight cellular concrete is used as interiorfill 512, drains 702, 804 may be included to facilitate drainage throughconcrete interior fill 512. Alternatively, once a sufficient amount offree-draining interior fill 512 such as crushed rock has been placed andcompacted, an upper portion 504 of the wall 500 may be cast in placeabove the interior fill 512, between the tee beams 506, 510.

FIGS. 6-8 depict the seawall 500 of FIG. 5 in cross section, at threesuccessive stages of construction. Referring to FIG. 6, the sheet-pilecut-off wall 516 is provided, and a crushed stone layer 610 is providedas a base for the tee beams of the footing 508. The tee beams areprecast concrete with a plurality of lower anchorages 608 and ducts 606for threadbar 514 (or multi-wire strand). The tee beams for the footing508 are cast with a void in the flange, and are positioned so that thevoid admits the top end of the sheet pile cut-off wall 516. With the teebeams for the footing 508, the seaward tee beams 510 are coupled to thefooting 508 and compressed via post-tensioned threadbar 514 as describedabove with reference to FIG. 2.

Referring to FIG. 7, the landward tee beams 506 are similarly coupled tothe footing 508 and compressed via post-tensioned threadbar 514. Drains702 are placed, and the crushed rock for the interior fill 512 is addedbetween the beams 506, 510, and compacted. Referring to FIG. 8, upperdrains 806 are placed, and the concrete (or similar material) to formthe upper portion 504 of the wall 500 is cast in place between tee beams506, 510. The upper portion 504 is confined to the interior of the wall500 between tee beams 506, 510, and may thus be cast without buildingadditional forms on either side of the wall 500. The upper portion 504may be cast from a flowable material such as concrete, cellularconcrete, or grout. Wave deflectors 502 are coupled to the upper portion504 of the wall 500, the threadbars 514, the landward tee beams 506and/or the seaward tee beams 510. “Burrito drain” inlets 804 are coupledto the lower drains 702, and fill material 802 is added to backfill thelandward side of the wall 500.

FIG. 9 depicts another embodiment of a seawall 900 in cross section, ata completed stage of construction similar to FIGS. 4 and 8. As in FIGS.4 and 8 the seaward side is depicted to the right, and the landward sideis depicted to the left. The seawall 900, in the depicted embodiment,may be substantially similar to the seawalls 100, 500 described abovewith reference to FIGS. 1-8, including wave deflectors 902, acast-in-place upper portion 904, landward tee beams 906, a footing 908,seaward tee beams 910, interior fill 912, threadbar 914, a sheet pilecut-off-wall 916, a crushed stone layer 1010, threadbar anchorages 1008,ducts 1002, 1006, access voids 1004, drains 1102, 1204, “burrito drain”inlets 1206 and fill material 1202, which may be substantially asdescribed above. Additionally, in the depicted embodiment, the wall 900includes multi-wire strand 1302 coupled to threadbar by a coupler 1304,as described below.

In various embodiments, post-tensioning steel for tee beams 906, 910 maybe multi-wire strand 1302 and/or threadbar 914. In various embodiments,post-tensioning steel may be vertical, angled at the same angle as theflanges of tee beams 906, 910, and/or angled at a different angle thanthe flanges of tee beams 906, 910. In the depicted embodiment,post-tensioning steel for seaward tee beams 910 is vertical threadbar914, and post-tensioning steel for landward tee beams 906 is multi-wiresteel strand 1302, angled at the same angle as the flange of thelandward tee beams 906.

With the fill material 1202 impinging on the landward tee beams 906,soil pressure on the exterior of the flanges for the tee beams 906 maycause or tend to cause deflection, resulting (in the absence ofpost-tensioning) in tension on the interior face of the flanges, whichmay weaken the landward tee beams 906. Thus, in the depicted embodiment,providing post-tensioning steel angled at the same angle as the flangesfor landward tee beams 906 may result in the entire flange being incompression. An anchorage 1008 and duct 1006 are disposed in the footing908 at the desired angle. A short piece of threadbar is coupled to theanchorage 1008 and extends out through the duct 1006 to provide anattachment point for multi-wire strand 1302.

A strand-to-threadbar coupler 1304 (as disclosed in the incorporatedpatent application referred to above) may include a threadbar nutcoupled to the exposed threadbar, and a strand chuck to which the strand1302 is coupled. The strand 1302 is coupled to an anchorage at the topof the tee beam 906, and is tensioned between the lower coupler 1302 andthe upper anchorage. Tension may be applied at the anchorage and/or atthe coupler 1302 (e.g., by torquing the threadbar nut before theinterior fill 912 is placed). In various embodiments, various other orfurther anchorages, couplers, and/or tensioning devices or methods maybe used to install and tension multi-wire steel strand 1302.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A seawall comprising: a concrete footing; aplurality of precast concrete tee beams comprising one or more ofsingle-tee beams and double-tee beams, wherein flanges of the tee beamsare positioned to form seaward and landward faces of the wall, and stemsof the tee beams are coupled to the footing between the seaward andlandward faces; and interior fill disposed between the seaward andlandward faces.
 2. The seawall of claim 1, wherein the flanges of thetee beams are positioned such that the seaward and landward faces of thewall are slanted and the wall is thicker at a base of the wall than at atop of the wall.
 3. The seawall of claim 2, wherein the stems of the teebeams extend further away from the flanges of the tee beams at the baseof the wall than at the top of the wall.
 4. The seawall of claim 1,further comprising: a first plurality of anchorages disposed in theconcrete footing; a second plurality of anchorages disposed at tops ofthe stems; and a plurality of elongate steel components extendingthrough the stems and tensioned between the first plurality ofanchorages and the second plurality of anchorages.
 5. The seawall ofclaim 4, wherein the elongate steel components comprise threadbar. 6.The seawall of claim 4, wherein the elongate steel components comprisemulti-wire steel strand.
 7. The seawall of claim 1, further comprisingone or more wave deflectors disposed above the tee beams, the one ormore wave deflectors comprising concrete shaped to deflect water.
 8. Theseawall of claim 1, wherein the tee beams forming the landward face ofthe wall are shorter than the tee beams forming the seaward face of thewall.
 9. The seawall of claim 8, further comprising an upper portion ofthe wall disposed above the tee beams forming the landward face of thewall and behind the tee beams forming the seaward face of the wall, theupper portion of the wall comprising cast-in-place concrete.
 10. Theseawall of claim 1, wherein the tee beams forming the landward face ofthe wall are equal in height to the tee beams forming the seaward faceof the wall.
 11. The seawall of claim 1, wherein the interior fillcomprises one or more of: cast-in-place concrete; andvibration-compacted crushed rock.
 12. The seawall of claim 1, furthercomprising a sheet pile wall extending downward from the footing toprevent erosion of soil under the footing.
 13. The seawall of claim 1,wherein the footing comprises cast-in-place concrete.
 14. The seawall ofclaim 1, wherein the footing comprises concrete tee beams.
 15. Theseawall of claim 1, further comprising a plurality of drains extendingthrough the wall and sloped to drain water from a landward side to theseaward side.
 16. The seawall of claim 15, wherein the plurality ofdrains comprises: at least one upper drain comprising an inlet disposedabove a soil level at the landward face of the wall; and at least onelower drain comprising a filtered inlet disposed below the soil level.17. A method comprising: excavating a location for placing a concretefooting for a wall; installing a sheet pile wall extending downward fromthe location; installing a concrete footing at the location, theconcrete footing comprising a first plurality of anchorages forthreadbars; coupling threadbars to the anchorages; placing a pluralityof precast concrete tee beams over the threadbars, the tee beamscomprising one or more of single-tee beams and double-tee beams, the teebeams positioned such that the threadbars extend through stems of thetee beams, and the flanges of the tee beams are positioned to formseaward and landward faces of the wall; coupling a second plurality ofanchorages to the threadbars above the stems of the tee beams;tensioning the threadbars between the first plurality of anchorages andthe second plurality of anchorages; and installing interior fill betweenthe seaward and landward faces.
 18. The method of claim 17, furthercomprising disposing a plurality of drains extending through theinterior fill between the seaward and landward faces.
 19. The method ofclaim 17, further comprising coupling one or more wave deflectors to thewall above the tee beams.
 20. A seawall comprising: a concrete footing;a first plurality of anchorages disposed in the concrete footing; aplurality of precast concrete tee beams comprising one or more ofsingle-tee beams and double-tee beams, wherein flanges of the tee beamsare positioned to form seaward and landward faces of the wall, and stemsof the tee beams are coupled to the footing between the seaward andlandward faces; a second plurality of anchorages disposed at tops of thestems; a plurality of elongate steel components extending through thestems and tensioned between the first plurality of anchorages and thesecond plurality of anchorages; interior fill disposed between theseaward and landward faces; and one or more wave deflectors disposedabove the tee beams.